Last major update issued on September 6, 2004 at 03:40 UTC.
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2004)]
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The geomagnetic field was quiet to unsettled on September 5. Solar wind speed ranged between 285 and 429 km/sec. A (currently) fairly low speed stream from coronal hole CH112 began to influence the geomagnetic field after 09h UTC.
Solar flux measured at 20h UTC on 2.8 GHz was 103.2. The planetary A
index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 8.5).
Three hour interval K indices: 11222332 (planetary), 11322332 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 3 spotted regions on the visible disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10667 developed a few trailing spots (which were incorrectly assigned as a new region 10670 by SEC).
Region 10668 decayed slowly and quietly.
New region 10669 emerged in the southeast quadrant.
September 3-5: No obviously Earth directed CMEs were observed. Two full halo CMEs were observed on September 3, both from a centrally placed backsided source. Another full halo CME was observed on September 4, probably from the same backsided source. It will be interesting to see the region causing this activity when it rotates into view on Sept.10-11.
Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28
days ago 27 days ago 26 days ago
A recurrent coronal hole (CH112) in the northern hemisphere was in a geoeffective position on September 3-5.
Processed SOHO/EIT 284 image at 19:06 UTC on September 5. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on September 6-8 due to coronal hole effects.
| Coronal holes (1) | Coronal mass ejections (2) | M and X class flares (3) |
 |
|
|
1) Effects from a coronal hole could reach Earth within the next 5 days. When the high speed stream has arrived
the color changes to green.
2) Material from a CME is likely to impact Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.
Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor at night and good during local sunrise. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: none, several weak signals from North America noted. The only stations with good signals during the night was WWZN on 1510 and Greenland on 650 kHz, the latter signal was actually very strong.
Compare to the previous day's image.
Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SEC. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SEC or where SEC has observed no spots. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.
| Active region | Date numbered | SEC spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10666 | 2004.08.29 | N16W61 | plage | ||||
| 10667 | 2004.09.01 | 4 | 6 | S11E23 | 0250 | HKX |
classification was CHO at midnight, location S12E25 |
| 10668 | 2004.09.03 | 6 | 4 | S11W64 | 0050 | CAO |
classification was CSO at midnight, area 0030 |
| 10669 | 2004.09.05 | 7 | 6 | S06E35 | 0030 | BXO |
classification was DSO at midnight, area 0050 |
| 10670 | 2004.09.05 | 2 | S14E34 | 0010 | AXX |
these are the trailing spots of region 10667, this region should be deleted |
|
| S449 | emerged on 2004.08.30 |
S14W41 | plage | ||||
| S450 | emerged on 2004.09.04 |
S01W47 | plage | ||||
| Total spot count: | 19 | 16 | |||||
| SSN: | 59 | 46 | |||||
| Month | Average solar flux at Earth |
International sunspot number | Smoothed sunspot number |
|---|---|---|---|
| 2000.04 | 184.2 | 125.5 | 120.8 cycle 23 sunspot max. |
| 2000.07 | 202.3 | 170.1 | 119.8 |
| 2001.12 | 235.1 | 132.2 | 114.6 (-0.9) |
| 2003.07 | 127.7 | 83.3 | 61.8 (-3.2) |
| 2003.08 | 122.1 | 72.7 | 60.1 (-1.7) |
| 2003.09 | 112.2 | 48.7 | 59.6 (-0.5) |
| 2003.10 | 151.7 | 65.5 | 58.2 (-1.4) |
| 2003.11 | 140.8 | 67.3 | 56.8 (-1.4) |
| 2003.12 | 114.9 | 46.5 | 54.8 (-2.0) |
| 2004.01 | 114.1 | 37.7 | 52.0 (-2.8) |
| 2004.02 | 107.0 | 45.8 | 49.3 (-2.7) |
| 2004.03 | 112.0 | 49.1 | (47.0 predicted, -2.3) |
| 2004.04 | 101.2 | 39.3 | (44.8 predicted, -2.2) |
| 2004.05 | 99.8 | 41.5 | (41.5 predicted, -3.3) |
| 2004.06 | 97.4 | 43.2 | (38.6 predicted, -2.9) |
| 2004.07 | 119.1 | 51.0 | (36.8 predicted, -1.8) |
| 2004.08 | 109.6 | 40.9 | (35.4 predicted, -1.4) |
| 2004.09 | 96.6 (1) | 5.0 (2) | (34.2 predicted, -1.2) |
1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC) sunspot number. The official international sunspot number is typically
30-50% less.
This report has been prepared by Jan Alvestad. It is based partly on my own observations and analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.
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